20,871 research outputs found
Entanglement transfer from continuous variables to qubits
We show that two qubits can be entangled by local interactions with an
entangled two-mode continuous variable state. This is illustrated by the
evolution of two two-level atoms interacting with a two-mode squeezed state.
Two modes of the squeezed field are injected respectively into two spatially
separate cavities and the atoms are then sent into the cavities to resonantly
interact with the cavity field. We find that the atoms may be entangled even by
a two-mode squeezed state which has been decohered while penetrating into the
cavity.Comment: 5 pages, 4 figure
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Rapid Fabrication of Large-sized Solid Shape using Variable Lamination Manufacturing and Multi-functional Hotwire Cutting System
Rapid prototyping (RP) technologies have been widely used to reduce the lead-time and
development cost of new products. The VLM-ST process has been developed to overcome the
currently developed RP technologies such as a large building time, a high building cost, an
additional post-processing and a large apparatus cost. However, the VLM-ST process has the
limitation of fabricated model size (VLM300: 297×210 mm, VLM400: 420×297 mm) and the
limitation of slope angle when the large-sized model more than 600 × 600 × 600 mm or
axisymmetric shape is fabricated. The objective of this paper is to develop a multi-functional
hotwire cutting system (MHC) using EPS-foam block or sheet as the working material in order to
fabricate a large-sized shape more than 600 × 600 × 600 mm. Because the MHC apparatus
employs a four-axis synchronized hotwire cutter with the structure of two XY movable heads and
a turn-table, it allows the easy fabrication of various 3D shapes, such as (1) an axisymmetric
shape or a sweeping cross-sectioned pillar shape using the hot-strip in the form of sweeping
surface and EPS foam block on the turn-table, (2) a polyhedral complex shape using the hotwire
and EPS foam block on the turn-table, and (3) a ruled surface approximated freeform shape using
the hotwire and EPS foam sheet. In order to examine the applicability of the developed MHC
apparatus, an axisymmetric shape, a polyhedral shape and a large-sized freeform shape were
fabricated by the apparatus.Mechanical Engineerin
Meta-Stable Brane Configurations by Adding an Orientifold-Plane to Giveon-Kutasov
In hep-th/0703135, they have found the type IIA intersecting brane
configuration where there exist three NS5-branes, D4-branes and anti-D4-branes.
By analyzing the gravitational interaction for the D4-branes in the background
of the NS5-branes, the phase structures in different regions of the parameter
space were studied in the context of classical string theory. In this paper, by
adding the orientifold 4-plane and 6-plane to the above brane configuration, we
describe the intersecting brane configurations of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua of these gauge
theories.Comment: 21 pp, 6 figures; reduced bytes of figures, DBI action analysis added
and to appear in JHE
Efficient Schemes for Reducing Imperfect Collective Decoherences
We propose schemes that are efficient when each pair of qubits undergoes some
imperfect collective decoherence with different baths. In the proposed scheme,
each pair of qubits is first encoded in a decoherence-free subspace composed of
two qubits. Leakage out of the encoding space generated by the imperfection is
reduced by the quantum Zeno effect. Phase errors in the encoded bits generated
by the imperfection are reduced by concatenation of the decoherence-free
subspace with either a three-qubit quantum error correcting code that corrects
only phase errors or a two-qubit quantum error detecting code that detects only
phase errors, connected with the quantum Zeno effect again.Comment: no correction, 3 pages, RevTe
Meta-Stable Brane Configurations with Seven NS5-Branes
We present the intersecting brane configurations consisting of NS-branes,
D4-branes(and anti D4-branes) and O6-plane, of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua in four dimensional
N=1 supersymmetric SU(N_c) x SU(N_c') x SU(N_c'') gauge theory with a symmetric
tensor field, a conjugate symmetric tensor field and bifundamental fields. We
also describe the intersecting brane configurations of type IIA string theory
corresponding to the nonsupersymmetric meta-stable vacua in the above gauge
theory with an antisymmetric tensor field, a conjugate symmetric tensor field,
eight fundamental flavors and bifundamentals. These brane configurations
consist of NS-branes, D4-branes(and anti D4-branes), D6-branes and O6-planes.Comment: 34pp, 9 figures; Improved the draft and added some footnotes; Figure
1, footnote 7 and captions of Figures 7,8,9 added or improved and to appear
in CQ
Quantum Friction of Micromechanical Resonators at Low Temperatures
Dissipation of micro- and nano-scale mechanical structures is dominated by
quantum-mechanical tunneling of two-level defects intrinsically present in the
system. We find that at high frequencies--usually, for smaller, micron-scale
structures--a novel mechanism of phonon pumping of two-level defects gives rise
to weakly temperature-dependent internal friction, , concomitant to the
effects observed in recent experiments. Due to their size, comparable to or
shorter than the emitted phonon wavelength, these structures suffer from
superradiance-enhanced dissipation by the collective relaxation of a large
number of two-level defects contained within the wavelength.Comment: To apear in Phys. Rev. Let
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